1. Field of the Invention
This invention relates to signal generator circuits and, more particularly, to a novel and highly-effective signal generator circuit for generating a synchronization signal, a display clock signal and similar signals for a television receiver employed in a character and picture image information system such as a videotex or CAPTAIN (character and pattern telephone access information network) system and which uses, for example, a telephone network line for signal transmission.
2. Description of the Prior Art
In the videotex and CAPTAIN character and picture image information systems and similar systems using a color television receiver as a display apparatus, there are required signals such as vertical and horizontal synchronization signals, a color sub-carrier signal (for example, a signal having a frequency of substantially 3.58 MHz) and a display clock signal (for example, a signal having a frequency of substantially 5.727 MHz). When character and picture information is displayed on the screen of a television receiver, the display portion in the horizontal direction is determined with reference to the horizontal synchronization signal: i.e., such information is displayed at a predetermined position (time) with respect to the position (time) of the horizontal synchronization signal. To indicate such display position, a special pulse is generated. The position of the special pulse is determined by the operation of a counter which begins at a time which, because of deficiencies in the prior-art structures, may change by one clock period in successive horizontal lines. This of course correspondingly displaces the display position pulse so that a jitter appears in a reproduced picture in the horizontal direction on the screen of the television receiver.